Generator equalizer control system



March 2, 1954 5, GILLESPIE 0 2,671,175

GENERATOR EQUALIZER CONTROL SYSTEM Filed April 24, 1950 IN VEN TOR.

HTTOK/VEY Patented Mar. 2, 1954 2,671,175 GENERATOR EQUALIZER CONTROL SYSTEM Harold S. Gillespie, Hasbrouck Heights, N. J., as-

signor to Bendix Aviation Corporation, Teterboro, N. .I.,

a corporation of Delaware Application April 24, 1950, Serial No. 157,770 6 Claims. (Cl. 307-87) The present invention relates to a generator control system and more particularly to a novel equalizer disconnect system.

In multi-generator D. C. aircraft generating systems, the conventional practice is to control the connection of the individual generators to the bus by means of a differential voltage and reverse current relay. One of the functions of the aforenoted relay is to energize the control circuit for the main contactor thereby to connect the generator to the bus, upon the generator voltage rising slightly above the bus voltage, say for example, volt above the bus voltage. Another function is to deenergise the control circuit of the main contactor thereby disconnecting the generator from thebus, when-the generator draws a predetermined amount of reverse current.

In order to bring the voltage of a generator above the bus voltage whose normally regulated voltage is the same as that of the bus voltage, it is necessary to connect the equalizer coil of the oncoming generator to the equalizer bus. Due to the difierence in loads, the equalizer coil of the oncoming generator will tend to raise its voltage while the equalizer coils of the generators on the line will tend to depress the bus voltage thus permitting the oncoming generator voltage to rise sufliciently above the bus to actuate the differential voltage and reverse current relay to connect it to the bus.

Also, it is desirable to disconnect the equalizer coil of a generator going off the line as soon as possible in order that the bus voltage may rise to its normal value. p

Heretofore, it has been the practice in some sys ems to connect and disconnect the equalizer coil by means of a relay responsive to generator voltage. A disadvantage of the aforenoted means for connecting the equalizer coil in the system is that the pick-up and drop-out voltages at which it is practical to operate the re-' lay are such that the coil is connected in at a lower voltage than desired. For example, in a 28 volt system the relay closes when the generator voltage reaches approximately 22 volts. Also the drop-out voltage is lower than that desired, for example, 18 volts or lower. The lower the operating voltage of the relay, the longer time it is necessary to operate with the bus voltage depressed. In some instances, upon the generator going off the line due to reverse; current but remaining at idling speed, the generator voltage will be above the drop-out value, hence the bus would operate continuously at a de-' pressed voltage. The present invention provides a system for connecting the equalizer coil just before the generator goes on the line and disconnecting it immediately after the generator goes off the line. A relay which operates on differential voltage shorts out the operating coil of equalizer relay until the generator voltage nears that of the bus voltage.

It is an object of the invention to provide an improved generator control system.

Another object of the invention is to provide improved means for connecting and disconnecting the equalizer circuit in a generator system.

Another object of the invention is to provide means for connecting an equalizer winding into a generator system at near bus voltage.

Another object of the invention is to provide means for disconnecting the equalizer coil immediately upon the generator going 01f the line.

These and other objects and features of the invention will appear more fully hereinafter from a consideration of the following description taken in connection with the accompanying drawing wherein one embodiment of the invention is illustrated by way of example.

In the drawing:

The single figure is a schematic diagram of a generator and associated control circuits embodying one form of the invention.

Referring to the drawing, there are shown load lines or buses and 2 adapted to be supplied by a plurality of generators which may be of any suitable type. By way of example, two generators 3 and 3a are shown which may be driven by any suitable means, such as an aircraft engine (not shown). It is understood, however, that any number of generators may be used.

The generator 5': shunt field winding 5. The winding 4 is connected'in series with one output brush of the generator 3 and the bus 2 by a conductor 5. The other output brush of the generator I is connected to the bus through a switch member 1 by a conductor Leading from the shunt field winding 5 is a conductor s which in turn is connected to one end of a variable resistance carbon pile element it a regulator H. The other end of the carbon pile element it is connected by a conductor IE to the output line 13.

Winding-s i3 ondl i provide electromagnetic means which are so arranged in the carbon pile regulator l i to control an armature 15 thereof and thereby the pressure pile element E0. The regulator H is shown diahas a series winding 4 and a applied to the carbon grammatically in Figure 1 as including the armature l5 pivoted at 16 and exerting a compressive force upon the carbon pile under tension of a spring H. The spring I! is arranged so as to balance the pull on the armature l5 by the windings l3 and id for a predetermined output voltage. One end of the winding i3 is connected to erator 3 as the series windingv 4 Theother endof the winding 14 is connected-teen-equalizer bus 2| through a switch member 22 by conductor 23.

The switch is normally biased in an open circuit positi n by spring 24 and is actuatedto a closed position by electromagnetic winding 25.

i'e wi-ndicig zfi ristconneotedrto t of thecwimiing': 25" S'PCOHIlfifiiSBd r Z'ito one 'contactcf aswitclrmema differential voltage and: reverse: cur- 2,-- The other contact oi'sithe'switch member 21 connected; by is: conductor 2.9:to .the output" line it.- A manual switch so may" be-inserted in the conductorriiiii'.

The relay "28 istoizthe-rpolarizedv magnetic latching type and isficontrolleclihythe u ec-t-romagnetic windings: 3i and 332-. One end. of. the windingi is connected a conductor tothe conductor 2%. lhieio' 'c iisconnecteri to conductori w totthe has 21 issoarrang to actuate.tl'leswitch member?! sen posi tion when the reverse "currentfiowing in. erator '3 exceeds. a predetermined amount:v

2 connected across th swit 1-11 or of switch inxseries-i I My. hy-connuctors. 3'1; 38" and. am: so an ed to-actuatetheswitch memberlttoa closed .tion whenthegenerator. voltage. is greate tnamthezline voltagewbyi apredetermined amount;

The switchimcmcerflz is -biased .by springtowards a circuit-open position'and..istactuated andrhel'd: in a; closed positionby electromagnetic winding i'i; One-end ofthe windingfi i. is. 60511? n cted by conduetorJL-i :to the conductcrlii which i atu'rn i -cormectedrtothe ouitputicondnctoriiil heezothei endiof tthezwindingM is connected to hroughrresistor 43.- Thewinding 4! is asito actuate the. switch. member 22 positi'onupon the generator voltage re ermineri; value.

The: as 35 of relay- 3E is. so.atrangcri.to actuate tch member Mctoa. closed" position upon the voltage of the generator differing from the veltageioithe linehy a predetermined. amount of a; given polarity. The switch.member is nor.- mall-y biased. to a an opencircuit position. by a spring 15. contact 0t theswitchmemher M isaconniected by a conductor saw one end of the winding Mend the other contact ofthe member iiris connected by conductor 4'5. to the other of" the winding 4i so that when the switch. M 'is'inthe' closedposition, the winding 4 I is fshort-circuit'ed.

likewise, the generator So has a series winding do and a shunt winding 5a and is connectcdto' the hates i in the same manner as the generator; 3. Pai't'sin' the generator 3a have been given the ;same-.reference numerals; with the let-- ten-o added, todis'tihguish therefrom as the corresponding partsin the genera-tori Inas=- to cl reaching a.

much as the two are similar, a detailed description of the generator 3a will be omitted.

In operation, the winding 4| responsive to generator voltage actuates the switch contact 22 to connect and disconnect the equalizer winding l4 in the system. However, the winding 4! is subject to the control of the relay 35 which shortcircuitsathewindihg 4| iwhen theirgemerator voltage is a predeterminedamountwelow" the bus voltage. The relay 35 is polarized and operates on differential voltage.

When thergenermtor voltage is building up and approaches the bus voltage within, for example, approximately GLYvolt, the spring overcomes 36 and opens the contact 44 to remove the short circuit from the winding 4-1 wrhiiclrithien iaactuates the switch 22 to connect the equalizer circuit in the system. Upon the busb'eing loaded, the equalizer circuit will cause the regulator H to boost the voltage of the oncoming generator s sufiiciently aboveibnswolta'ge to operate the (inferential voltage reverse. current relay and connect the -generator: 3 -to tkmcbtmi- Wheneverthe generator voltagesciropsza predetermined 1 amount below the? has voltages. tor example; 1' volt, such as. just iafterza reverse-1cm; rent openingzthearelay. 3d overcomes therbiasmi the spring fluandacloses the.Iswitch"zims'rnher."M thereby shorting-out the winding 3M: tuopen time equalizer ci'rc-uiit.

Although only' one embodiment: oi? the inven ticnhasibecn illustratediand. described,- various changes ilflithe iormiandrelative arrangements oi thefpai e may be made to snit requiirementse.

What isclaimedsis:

1. In :combinatiom. aloadcircuit a plurality ,ul generators for said load circnit voltageeregulate ing means associated with each of said generators; relay means associated witlr at least onegenerator for connecting. said generator into. the-"Matthicuit upon the lgeneratedicurrent of said generator exceeding-the loa 'cin'rent bya predetermined value, saidregulatorszarrangcd so asztosmmintain a. predetermined generator: voltage; meamt in-w :e cloding'faniequalizer circuit .for varying-thatch.-

. erator upon the voltage of saidigeneratonbeina below the-*voltaige oi: said load: circuit.- byaa wedeterminediamount.

22.1.mcombinatiorna main. output-line, aaphn rality roizgenerators; each ofssaidgenerator'aehav an ontputwoixtagesregulator; reverseectmreat andidifierenti'al voltage relay mcanswtormontrok ling the connection of :the associated gencmtoato said outputwlinanani equalizer circuit-associated with saia regulators SOJ'ASWO maintaimatpsew termined division of load between said generators: equalizer disconnect relay means reaponsive tattle voltage-of the associatedgenerator. for ling the connection of: said regulator-to we equalizercircuit; and meanaarespensiveito the difierenceimwoltagresbetween'sacebassociated gas; erator: and saidoutputcline to shnm'rsara Ieqmfler disconnect" relay v means: upon: said difiecen'cs m voltage-exceeding 5,: predetermmcu emeanr fire predetermined direction;

3. In combination;- w-mammpwim spre rality of generators, each of said generators having a field circuit, an output voltage regulator winding, an equalizer bus means.

paratus for use in controlling the con- 5. AP nection of a generator to a load circuit in a generator to said load circuit,

and third relay means responsive to said differential in voltage for short circuiting said first relay means upon said differential in voltage exceeding a predetermined value.

crease the voltage setting of the regulating means of the generator disconnected from the load circuit, comprising first relay means normally biased to an open circuit generated voltage of said disconnected generator to overcome said bias and actuate said first relay circuit by a predetermined amount.

HAROLD S. GILLESPIE.

References Sit-ed in the file of this patent UNITED STATES PATENTS Number Name Date 2,401,795 Rady June 11, 1946 2,483,117 Almassy Sept. 27, 1949 2,494,397 Lusk Jan. 10, 1950 

